Category Archives: Obstetrics

Contributors Dr Toby Shipway and Flight Nurse Jodie Martin return with a little about something that would make any retrievalist sweat – delivering babies in the air.

A call came into the Logistics Coordination centre from a nurse in a remote health centre, worried about new contractions in a pregnant woman who was 31 weeks pregnant. We decided to take a full retrieval team for the ‘just in case’ scenario. Afraid of getting caught out, we had a big discussion to make sure we had all the right gear on board the aircraft and what our plan of action would be should we be faced with the rare event of an inflight birth. Why worry though? They’re rare, right?

We retrieved the woman from a remote airstrip and it became evident just after takeoff that she was in established labour. Even after tocolytic therapy, the preterm baby was born at the start of descent into Darwin. No one on the plane will forget the midwife examining the patient, looking up wide-eyed and shouting calmly down the plane ‘its coming out now’. Never has a pilot descended at such a pace. After initial resuscitation of the baby, both mum and baby did well and were transferred safely to the hospital. Phew.

The sort of view you don’t get to enjoy when it starts getting imminent.

The Big and Little Numbers

Four cases were found on searching through the database over a four-year period from 2011 to 2015. Over that four-year period there were 1311 retrievals associated with Obstetrics and Gynecology, out of a total number of 15967 retrievals in the NT. This means obstetric and gynecology related retrievals account for approximately 8.2% in our aeromedical retrieval service.

Looking at the obstetric retrievals in more detail, there were 436 cases associated with pre-term labour of which 4 progressed to in-flight births. This equates to an incidence of 0.92% of all women transferred in preterm labour. It is not a common clinical situation.

Case one was a 37 year old woman of gestational age 36+5 weeks, gravida 5 para 2. The retrieval was tasked in the early hours at 0010. Take off was at 0050 and contact was made with the patient at 0145 at the airstrip. She was contracting 3:10 at this point. Tocolytics had been administered according to protocol, which was 3 separate doses of nifedipine 20 mg initially, at 30 mins and at 1 hour. Return takeoff was at 0210 with progression to spontaneous vaginal delivery of the baby at 0245. 10 unit of syntocinon was administered intramuscularly with approximately 300 mL of blood loss measured with delivery of the placenta. Apgars of 61 and 95 were recorded. Both baby and mother were discharged at 3 days from hospital with routine follow-up from the community nurse.

Case two was a 25 year old woman of 31week’s gestation, G2P1 – this was the case from the top. Again this was an early morning flight, tasking was at 0052 and take off was 0128. Patient contact was made at 0250, where the patient walked onto the plane contracting 1:10. The clinic team had given nifedipine as per protocol. Return takeoff was at 0300 with progression to spontaneous vaginal delivery at 0400. Apgars were 61 and 85 with the baby needing some supportive ventilation. Mother and baby were transferred to hospital where on assessment in the neonatal unit positive pressure ventilation was stopped. Length of stay for this little one with intrauterine growth retardation was 22 days; there were no complications with the mother.

Case three was a 31 year old woman of 22 week’s gestation, G6P2. This one came up in a previous post as it involved a complicated resuscitation of mother and baby. The midwife was en-route back to home base on another task when the referral call to divert to this case was made. This again was in the early morning with the re-tasking occurring at 0330. On assessment at 0450 the patient was contracting 3:10, and the clinic reported a large clot was passed in clinic. Return takeoff was at 0500, with progression to spontaneous vaginal delivery at 0522. Apgars were recorded as 61 55 510 as neonatal resuscitation was ongoing. The mother delivered the placenta at 0548, which was accompanied by a PPH of 1 L dropping maternal BP to 42/38. Fundal massage and a blood transfusion were started. On landing the retrieval team was met by a ground crew – the neonate was transferred in a separate ambulance with ongoing resuscitation by the Medical Retrieval Consultant and a flight nurse. On reaching the Emergency Department the multi-disciplinary team decided to cease resuscitation of the baby at 0645. The mother received further blood products and stayed in hospital for 4 days.

Case four was a 26 year old woman of 28+5 week’s gestation, G2P1. This was the only retrieval in daytime hours with tasking at 1040 and take off recorded as 1135. The retrieval team went into clinic on arrival, making contact at 1245. On assessment the patient was contracting 1:10. Return takeoff was at 1345 and patient passed a large blood clot at 1410 with rapid progress to spontaneous vaginal delivery at 1418. Apgars recorded were 61 95 and some respiratory support with nasal high-flow was given. The placenta was passed at 1425 and the total blood loss was estimated to be 250 mL. The patient had no documented cardiovascular instability. The patient and baby were transferred to hospital with no further issues. However the baby stayed in hospital for 66 days needing long-term respiratory and feeding support. It was diagnosed with a dilated cardiomyopathy and on follow-up review was listed for a heart transplant.

What About the Treatment?

All women received the recommended preterm labour treatment, being intravenous antibiotics and steroid therapy. Three out of four patients received tocolysis – the fourth case did not as the blood clot passed in clinic was deemed a contraindication. It was reported vaginal examinations upon referral were conducted in 3 out of 4 of these cases. Interestingly, the reports of those examinations found the cervix to be closed or an undetermined dilation. It goes to show that despite our best estimates from a physical examination we need to be prepared that inflight birth may in fact occur, even though it is a rare occurrence.

In transferring women in pre-term labour, the aim is to keep the baby in utero, as the evidence relevant to our setting indicates that in utero transfer is associated with much improved maternal and neonatal outcomes. The NT has a particularly high proportion (10.6%) of preterm births prior to hospital arrival and although multifactorial the large distances are likely to play a significant role. Prompt retrieval and the involvement of a team with the right skill mix to make a detailed obstetric/midwifery risk assessment would hopefully lessen the chances of inflight birth. But very rare still doesn’t mean never.

We welcome another new contributor to the site with this post. Jodie Martin is a clinical educator and flight nurse working in the Top End of Australia. She has just finished up a Masters which included looking at a big retrieval challenge – preterm births in the wild reaches of the Northern Territory.

Which retrieval taskings scare you the most? Is it the paediatric trauma patient in the prehospital setting, a long way away from the nearest trauma setting? Or perhaps the critically unwell and septic neonate in a remote clinic, which you know will take you 6 hours to retrieve to a hospital?

For me, it’s the women in preterm labour. Even after 10 years of flight nursing, it’s the women in preterm labour that make me nervous. And before I became a flight nurse I’d been a midwife for several years, working in rural and remote settings where I became fairly comfortable caring for obstetric patients in an isolated setting, because you had to be really. Aeromedical retrieval teams are rarely as quick as you’d like out there.

So even after a lot of exposure to obstetric patients in isolated areas, it is the preterm labour cases which make me sit on the edge of my seat. These are the cases I really want that crystal ball so we can foresee what is going to happen; is this woman going to deliver before we get there? Do we need to spend time on the ground to wait for birth or can we risk it and transfer her in labour and get her to hospital in time to allow preterm birth in a tertiary health centre? How will I manage an unexpected birth of a preterm baby during flight? Do I need to take all of the 100kg+ neonatal equipment to care for a preterm neonate? Do we need a paediatrician, just in case?

A Brief History of Stopping Labour in the Top End

In 2009 or there about, obstetric services in the Top End of the NT moved away from using IV salbutamol and started using nifedipine as the tocolytic of choice. This was because nifedipine was seen as a safer tocolytic with less adverse maternal side effects. In particular, there is a high incidence of rheumatic heart disease in the NT and we now had a better option of avoiding the negative effects IV salbutamol can have on cardiac function.

We already knew that facilitating in utero transfer of preterm babies improves their outcomes so that was still our aim. 1 However, I was yet to be convinced nifedipine was a superior choice for the aeromedical transfer of women in preterm labour.

So we turned to the literature to find out about the incidence of inflight births and to determine what happens to the women in preterm labour transported by aeromedical retrieval. Some studies reported no births occur in flight.2 However these studies utilise different types of tocolytics than our aeromedical retrieval service. A Canadian aeromedical retrieval service did report inflight births. 4 of these births occurred despite tocolysis but that tocolytic was not a calcium channel blocker such as nifedipine and the other births received no tocolysis at all 3. Anecdotally we knew at CareFlight NT we’d had 3 inflight preterm births despite nifedipine being administered. In three different Australian based studies which reviewed the transfer of rural and remote women, approximately 50% are in fact discharged.2,4,5

So what about the risks for pregnant women in the Northern Territory? Unfortunately, the news is not good. The NT has the highest rate of preterm births in Australia with 10% of all births occurring before arrival to hospital.6 Indigenous women and newborns do worst on some birth outcomes if they live in a remote area of the Top End of the NT7 and the NT has the highest maternal death rate in Australia.8 So being an Indigenous pregnant woman in a rural remote area of the NT is a combination of a lot of significant risk factors.

Let Me Paint You a Picture of Where We Work

The Top End is a geographical area twice the size of the UK & a just a little smaller than Texas, so around 400,000km2. There are two small rural hospitals which undertake planned low risk, term births. Both hospitals have emergency obstetric and caesarean capability along with the ability to provide immediate neonatal emergency care, but have limited resources to care for a preterm newborn for any extensive period of time.

There are over 35 small remote health centres we service. These health centres have no inpatient facilities and do not perform planned births. These centres can sometimes manage an unexpected normal birth but have no theatre or neonatal nursery care resources. Sometimes there is a remote area midwife available.

There’s only one NICU, which is located at Royal Darwin Hospital. The next closest NICU is 3,027km away in Adelaide. So when a woman presents in preterm labour in a rural or remote area in the Top End of the NT there is a natural level of anxiety as resources are limited, retrieval times can be long and we know we have a high risk obstetric population.

So I thought it was worth looking at our own data on the women we transport in preterm labour to find out more about their outcomes. Plus I needed to do a research project to complete a Masters’ degree.

The aim of our 3 year retrospective study was to determine the outcomes of women in preterm labour transported by aeromedical retrieval. We reviewed all the cases of preterm labour referred to CareFlight NT. Preterm labour was defined as 23+6 to 36+6 weeks gestation with a viable pregnancy. We excluded those women who had been referred after a preterm birth had already occurred. After exclusions for missing & incomplete data, we ended up with a sample of 304 women referred in preterm labour. We examined discharge data at Royal Darwin Hospital to review the outcomes.

What we found

Demographics and retrieval timesThe average gestation was 32+2 week and 90% of the women we transferred were Indigenous (there’s that high risk obstetric factor again I mentioned previously).

Retrieval time was taken from time of referral to our logistics coordination unit (LCU) to time of handover at the receiving hospital. Average retrieval time was 5.55hrs. Those women who proceeded to a preterm birth had an average time of birth following referral as 5hrs. Therefore there will be times when a preterm birth occurs before we can get to our destination.

Where preterm birth occurredThe places where women did give birth to a preterm baby:

16% in a remote health clinic

7% in a rural hospital

73% in RDH – the only tertiary health centre in the Top End with neonatal intensive care capabilities

4% elsewhere -3 births occurred in flight, 1 on the tarmac of a remote airstrip and 1 interstate.

Yes of course, this is exactly where we’d like to be setting up for a preterm delivery.

Nearly half of all preterm births which occurred in a rural hospital had been transferred from a remote community to a rural hospital instead of the tertiary centre. It is thought the rural hospital may have been chosen as a destination on occasions it was closer than Royal Darwin Hospital from the referral site and the long transfer was thought likely to end with an inflight birth. This reflects the decision making clinical crews have to be able to make on the run. Detailed midwifery and obstetric assessments and sound judgement are vital skills that the teams have to deploy when faced with the aeromedical retrieval of pregnant women in preterm labour.

Who went on the flights79% of all retrievals in this cohort were conducted by a flight nurse/midwife alone; 15 (or 44%) of all preterm births occurred outside of any hospital (being a rural or tertiary hospital) with a flight nurse/midwife only crew. This certainly highlights the importance and requirements for ongoing education and training in midwifery, obstetric emergencies and neonatal resuscitation for our flight nurse/midwives plus our rural and remote health colleagues.

Slightly less pressure here.

14% (n=42) of all preterm labour referrals included a CareFlight flight doctor + flight nurse/midwife mix, with 12 preterm births occurring prior to arrival to a tertiary health centre. A paediatrician/paediatric registrar went on 23 taskings (7%) and their skills were required in 5 cases where a preterm birth occurred whilst another 6 of these cases with a paediatrician/paediatric registrar resulted in the woman being discharged with no preterm birth occurring.

TocolysisWhat about the transfer of women in labour after they’d had nifedipine? About half of the women were still contracting upon handover at the receiving hospital whilst 42% had stopped contracting upon handover. 13% of referrals of women in preterm labour delivered a preterm baby prior to arrival at a tertiary health centre despite tocolysis, which could reflect women presenting late in labour & nifedipine not being useful in these and other instances.

Birth outcomesIn aiming to facilitate preterm birth in a tertiary hospital, there will always be a proportion of women who are subsequently transferred and do not go onto give preterm birth. We had a discharge rate of 49% where no preterm birth occurred. Our findings are comparable to other Australian studies. One previous study reported 53% of women in Western Australia transferred by aeromedical retrieval were discharged without birth occurring2 and another study reported 46% of women from rural areas in New South Wales were discharged following transfer to a tertiary centre.5

Yet another study reported 42% of women were discharged without birth occurring following transfer and the authors suggested that remoteness was associated with increasing rates of antenatal transfer.4 This is evident in the results of our study as we found 4% of women were transferred two or more times during a current pregnancy, reflecting the remote nature of the area we service and the high risk obstetric population. We need to expect that in the interest of maximising outcomes for mothers and babies from rural and remote areas, facilitating preterm birth in a tertiary hospital will result in some unnecessary yet costly aeromedical retrievals.

Triage and priority coding

The majority of women were triaged and retrieved appropriately to facilitate aeromedical retrieval in a timely fashion to enable a preterm birth in a tertiary hospital (73%). Five out of the 11 preterm births in a rural hospital were initially planned for retrieval from a remote health centre to the tertiary hospital but were transferred to a rural hospital instead. This may have occurred as the aeromedical crew found the woman was in more advanced labour than anticipated and elected to choose the closer rural hospital. Other aviation factors such as adverse weather may also play a role in these decisions.

Thus triage and priority coding for women in preterm labour reflects accuracy in the need for prompt retrieval, but also sometimes later decisions by the retrieval team who are required to make judgements upon arrival as to whether to allow birth to proceed in an environment with limited resources or risk inflight birth. Decision making on triage and priority coding will always revolve around the facilities and skill of personnel at the referring site, distance, gestational age, cervical dilation, labour advancement and maternal and fetal risk factors.

Stuff this bit of research didn’t tell us

There were several limitations in our study, namely the small sample size and lack of stratification of obstetric risk factors. It was intended at the commencement of this study to report on the doses of nifedipine administered. However, due to lack of documentation and ability to clarify the doses administered, it was decided early in the data collection process to discontinue recording the doses. Thus it has been assumed the dose administered is in accordance with local clinical guidelines (oral nifedipine 20mg given 20-minutely to a maximum of 3 doses in 1 hour then 20mg 3 hourly)10. The doses of nifedipine actually administered may be different to that recommended and therefore the success of in-utero transfer may be dependent on the dose of nifedipine administered.

The Bit for the Fridge Magnet

So, the take home points when it comes to the aeromedical retrieval of women in preterm labour:

Prompt retrieval of women in preterm labour is vital to facilitate preterm birth in a tertiary health centre with neonatal intensive care facilities to improve neonatal outcomes or at least get the neonatal intensive care unit to the neonate in a timely manner;

Early and aggressive management of preterm labour with nifedipine improves the success of an in-utero transfer;

We have a high risk obstetric population in the NT – remember the importance of other preterm labour clinical guidelines such as the administration of steroids and IV antibiotics;

Send the right team at the right time. One member of the aeromedical retrieval should have an obstetric/midwifery background. It’s the detailed obstetric assessment which will assist a crew to make that decision of whether to stay and play or scoop and run, hopefully avoiding inflight birth and facilitating a successful inutero transfer to a hospital;

In the interests of improving maternal and neonatal outcomes, we have to accept that there will be some retrievals of women in preterm labour which weren’t required as a half of them will end up being discharged;

Flight crews and retrieval consultants make some tough decisions when it comes to the aeromedical retrieval of women in preterm labour…if only we could have that crystal ball. But at least we know we’re making the right decisions regarding flight crew mix, triage and whether to put a woman in preterm labour on an aircraft or wait on the ground for birth to occur.

And for more details I’ll just have to let you know when the publication hits the journals (very soon I hope …)

Notes:

The staff in those photos are OK with those being shared.

The image of MKT airstrip is a Creative Commons one from flickr and is unchanged from the original Ken Hodge posting.